In the drilling, or completion of wells traversing earth formations, the first section of borehole is drilled from the earth's surface to a selected depth and lined with a tubular pipe which is cemented in place and commonly referred to as a surface casing. In the next succeeding section of borehole drilled, a tubular pipe commonly called a liner is lowered into the borehole. The top of the liner is coupled to a liner hanger and the liner hanger is releasably connected to a setting tool. The setting tool is connected to a work string or drill pipe which lowers the liner into the open borehole below a casing until the liner hanger is adjacent to or near the lower end of the casing and the lower end of the liner is above the bottom of the open borehole. The liner carries conventional cementing equipment such as a cementing shoe, float collars and plug catchers. The borehole is filled with fluid such as drilling mud which is bypassed around the liner and liner hanger as the liner is run in the borehole. For a number of reasons it is desirable to have the outside of the liner or its diameter as large as possible to pass through the casing and the inside diameter of the liner hanger and liner which remains in the borehole as large as possible. Thus, as additional liners are disposed in drilled sections of a well bore, the size and length of the additional liners can be maximized thus enabling larger downhole liner bores at greater depths from the earth's surface. In other words it is desirable to minimize the effective annular wall thickness of a liner hanger as well as minimize the components of the liner hanger left with the liner in the well bore after the setting tool is released from the liner hanger and retrieved to the surface.
In an operation for hanging a liner, the liner and liner hanger are lowered through the mud or fluid filled surface casing and/or liners to the open borehole. When the liner reaches a desired location relative to an open borehole and an upper casing, a mechanism in the setting tool is actuated to move slips or slip members on the liner hanger from a retracted position to an extended position in engagement with the well casing. Thereafter, when weight is applied to the hanger slips, (i.e. the weight of the liner by slacking off on the drill pipe,) the slips are set and hang the liner in the well casing. Thereafter, the setting tool mandrel is again slacked off ("lowered") and rotated to the right by the drill string to rotate and release a lefthand threaded release nut on the setting tool from the liner hanger. Generally, the setting tool also has a sealing or pack-off device in sliding and sealing relationship to a bore in the liner hanger or liner after the setting tool nut is released from the liner hanger. At this time the setting tool is supported with the pack-off device in the sealing bore of the liner hanger so that there is a continuous bore from the earth's surface to the bottom of the liner. When cement is pumped through the continuous bore formed by the drill string, the liner, and the cementing equipment, the cement is displaced into the annulus between the liner and the borehole. Following cementing of the drill string in the open borehole, the setting tool is retrieved and the drilling or completion operations continued.
The setting tool can have hydraulically operated setting mechanism for the hanger slips or can have mechanically operated setting mechanism for the hanger slips. A hydraulically operated setting mechanism typically employs a hydraulic cylinder means which is actuated by pressure in the bore of the drill string. Pressure is obtained by dropping a pump down ball through the drill string to seat in a ball valve sleeve in the liner below the hydraulic setting mechanism. The ball valve sleeve is shear pinned to the liner and seats the ball so as to close off the bore of the valve sleeve. Thus, fluid under pressure is then used to actuate the hydraulic cylinder means to set the hanger slips. When the hanger slips are set, an increase in pressure permits shearing of the shear pin in the ball valve sleeve releasing the valve and opening the bore for subsequent application of cement.
In a mechanically set liner hanger, it is usually necessary to obtain a relative downhole rotation of parts in a setting tool and liner hanger to release the hanger slips or to release a spring force which mechanically acts upon the slips. The effect of a spring force upon release of the slips is to move the slips upwardly relative to an expander and also to move the slips outwardly. The hanger slips are then one-way acting in that the hanger and liner can be raised or lifted upwardly but a downward motion of the liner sets the slips to hang the liner in a well casing.
Separate hydraulic and mechanically operated devices have been separately incorporated in a well hanger and setting tool so that either setting device could be used for hanging a liner. The use of two different devices in a setting tool and liner hanger is desirable as trips in a well bore are expensive and time consuming. If the hydraulic mechanism fails or if resetting of a liner is contemplated, selective use of mechanical or hydraulic actuating means is desirable. However, such devices have heretofor required incorporation of parts of the actuators in the liner hanger and have involved long tool lengths.
The present invention is concerned with a hydraulic and/or mechanical setting tool for a liner hanger where the setting tool carries substantially all of the hydraulic and mechanical actuating devices in a single unit on the setting tool for retrieval with the setting tool. The liner hanger has a slip design which interacts with the setting tool mechanism and minimizes the annular wall thickness of the liner hanger and has substantial strength for supporting heavy and long liners.